Transmembrane tyrosine phosphatase and methods of use thereof

Abstract

The present invention relates to regulation and control of cellular processes by transmembrane protein tyrosine phosphatases, and to ligands that agonize or antagonize tyrosine phosphorylation mediated by such tyrosine phosphatases. This invention further relates to diagnosis and therapy based on the activity of such ligands. In particular, the invention provides a novel transmembrane protein tyrosine phosphatase-λ (PTPλ), nucleic acids encoding the same, antibodies to the PTPλ, and methods for identifying ligands to the PTPλ of the invention. A specific Example describes the isolation and characterization of the first chicken transmembrane PTP, called ChPTPλ. It has a unique extracellular domain containing a Ser/Thr/Pro-rich region, spectrin-like repeats, a fibronectin III domain, and an alternatively spliced N-terminus. The expression of ChPTPλ in various tissues and cells was also examined. ChPTPλ was shown to have a tyrosine-specific phosphatase activity, and the basic characteristics of this enzyme were studied.

What is claimed is: 
     
       1. An isolated protein that has an amino acid sequence consisting of amino acid 1 to 1237 of SEQ ID NO:2, or an amino acid sequence that differs from amino acid 1 to 1237 of SEQ ID NO:2 by only having conservative substitutions. 
     
     
       2. An isolated protein that has an amino acid sequence consisting of amino acid 22 to 1237 of SEQ ID NO:2, or an amino acid sequence that differs from amino acid 22 to 1237 of SEQ ID NO:2 by only having conservative substitutions. 
     
     
       3. An isolated protein having the amino acid sequence consisting of amino acid 22 to 509 of SEQ ID NO:2, or an amino acid sequence that differs from amino acid 22 to 509 of SEQ ID NO:2 by only having conservative substitutions. 
     
     
       4. An isolated peptide having the amino acid sequence consisting of amino acid 510 to 531 of SEQ ID NO:2, or an amino acid sequence that differs from amino acid 510 to 531 of SEQ ID NO:2 by only having conservative substitutions. 
     
     
       5. An isolated protein comprising the amino acid sequence consisting of amino acid 532 to 1237 of SEQ ID NO:2, or an amino acid sequence that differs from amino acid 532 to 1237 of SEQ ID NO:2 by only having conservative substitutions.